#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>

/* baudrate settings are defined in <asm/termbits.h>, which is
included by <termios.h> */
#define BAUDRATE B9600 // B38400            
/* change this definition for the correct port */
#define MODEMDEVICE "/dev/ttyUSB0"
#define _POSIX_SOURCE 1 /* POSIX compliant source */

#define FALSE 0
#define TRUE 1

volatile int STOP=FALSE; 

int main(int argc, char *argv[])
{
	int fd, res;
	struct termios oldtio,newtio;
	char buf[32];
	/* 
	Open modem device for reading and writing and not as controlling tty
	because we don't want to get killed if linenoise sends CTRL-C.
	*/
	fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY ); 
	if (fd <0) {perror(MODEMDEVICE); exit(-1); }

	tcgetattr(fd,&oldtio); /* save current serial port settings */
	bzero(&newtio, sizeof(newtio)); /* clear struct for new port settings */

	/* 
	BAUDRATE: Set bps rate. You could also use cfsetispeed and cfsetospeed.
	CRTSCTS : output hardware flow control (only used if the cable has
	all necessary lines. See sect. 7 of Serial-HOWTO)
	CS8     : 8n1 (8bit,no parity,1 stopbit)
	CLOCAL  : local connection, no modem contol
	CREAD   : enable receiving characters
	*/
	newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;

	/*
	IGNPAR  : ignore bytes with parity errors
	ICRNL   : map CR to NL (otherwise a CR input on the other computer
	will not terminate input)
	otherwise make device raw (no other input processing)
	*/
	newtio.c_iflag = IGNPAR | ICRNL;

	/*
	Raw output.
	*/
	newtio.c_oflag = 0;

	/*
	ICANON  : enable canonical input
	disable all echo functionality, and don't send signals to calling program
	*/
	newtio.c_lflag = ICANON;

	/* 
	initialize all control characters 
	default values can be found in /usr/include/termios.h, and are given
	in the comments, but we don't need them here
	*/
	newtio.c_cc[VINTR]    = 0;     /* Ctrl-c */ 
	newtio.c_cc[VQUIT]    = 0;     /* Ctrl-\ */
	newtio.c_cc[VERASE]   = 0;     /* del */
	newtio.c_cc[VKILL]    = 0;     /* @ */
	newtio.c_cc[VEOF]     = 4;     /* Ctrl-d */
	newtio.c_cc[VTIME]    = 0;     /* inter-character timer unused */
	newtio.c_cc[VMIN]     = 1;     /* blocking read until 1 character arrives */
	newtio.c_cc[VSWTC]    = 0;     /* '\0' */
	newtio.c_cc[VSTART]   = 0;     /* Ctrl-q */ 
	newtio.c_cc[VSTOP]    = 0;     /* Ctrl-s */
	newtio.c_cc[VSUSP]    = 0;     /* Ctrl-z */
	newtio.c_cc[VEOL]     = 0;     /* '\0' */
	newtio.c_cc[VREPRINT] = 0;     /* Ctrl-r */
	newtio.c_cc[VDISCARD] = 0;     /* Ctrl-u */
	newtio.c_cc[VWERASE]  = 0;     /* Ctrl-w */
	newtio.c_cc[VLNEXT]   = 0;     /* Ctrl-v */
	newtio.c_cc[VEOL2]    = 0;     /* '\0' */

	/* 
	now clean the modem line and activate the settings for the port
	*/
	tcflush(fd, TCIFLUSH);
	tcsetattr(fd,TCSANOW,&newtio);

	/*
	terminal settings done, now handle input
	In this example, inputting a 'z' at the beginning of a line will 
	exit the program.
	*/
	while (STOP==FALSE) {     /* loop until we have a terminating condition */
		/* read blocks program execution until a line terminating character is 
		input, even if more than 255 chars are input. If the number
		of characters read is smaller than the number of chars available,
		subsequent reads will return the remaining chars. res will be set
		to the actual number of characters actually read */
		res = read(fd,buf, sizeof(buf) -1); 
		buf[res]=0;             /* set end of string, so we can printf */
		printf(":%s:%d\n", buf, res);
		if (buf[0]=='z') STOP=TRUE;
	}
	/* restore the old port settings */
	tcsetattr(fd,TCSANOW,&oldtio);

	return 0;
}
